1. Field
The present disclosure generally relates to elevator systems, and more particularly, to an elevator system configured to be used with transportation vessels, such as aircraft.
2. Description of the Related Art
Transportation vessels, particularly aircraft, continue to grow in size, capacity, and operation frequency. Various design and operation parameters contribute to the operation of these vessels. While all parameters share particular requirements, such as safety, some parameters have conflicting requirements. For example, with respect to the aircraft industry, reducing aircraft weight and efficient loading and unloading can have conflicting requirements.
Loading and unloading equipment and devices is typically accomplished using ground equipment that is not integrated with and is external to the aircraft to reduce aircraft weight. However, these systems can hinder turn-around time and/or increase risk of damage to aircraft, making loading and unloading inefficient.
Furthermore, aircraft without integrated lift systems are limited to being loaded and/or unloaded in only certain locations such as adjacent airport terminals that have external loading and unloading devices.
Some designs have emerged in an attempt to improve loading speed and flexibility. Some designs suggest provisions to allow the carriage of an integrated elevator system to exit the aircraft. Existing designs propose certain structural support installations and motion systems that purportedly achieve this goal; however, generally there has not been a practical integrated lift system marketed for installation in aircraft, in particular, multi-deck aircraft.
One existing system employs a solid enveloping shaft and a heavy frame to support numerous pulleys mounted to the elevator cabin and to aircraft structure to move the cabin along guide rails. Such a system uses a heavy infrastructure, thereby requiring a heavy enveloping shaft to mount the infrastructure and guide rails. Even with such heavy structure, this system generally lacks multiple redundant failsafe braking features.
Furthermore, in such systems, the interface between the carriage and guide rails does not provide sufficient support for the cabin to entirely exit the fuselage. Existing railing and interface features can also result in an uneven or rough ride. In addition, the enveloping shaft inside the fuselage inhibits detection of fuselage structural damage, such as cracks and corrosion, from being detected until they propagate past boundaries of the enveloping shaft.
Another system employs a driven three-dimensional vehicle or cart mounted on the upper surface of the carriage, the cart having multiple wheels that can roll along rails. This system employs a motor driving a belt, the cart being fastened to the belt to move therewith. This system is difficult to repair and can be prone to frequent replacement of components that interface between the cart and motor. For example, belts can induce adverse lateral cart and carriage movement or oscillations. Additionally, the belt and the fasteners attaching the cart to the belt, typically require frequent inspections for belt wear and/or fastener degradation.
Typically, existing aircraft elevator designs also exhibit a primary load path toward the upper deck floor structure, significantly transferring load to, and stiffening, the upper deck floor structure. These designs generally do not provide any load limiting features. In such designs, the elevator support structure is usually rigidly attached to the upper deck floor structure. The upper deck floor structure plays an important role in providing support to the fuselage and is subject to heightened fatigue and damage tolerance ratings. This is especially the case in Boeing® 747® aircraft, the fuselage for which is made up of upper and lower portions having two distinct radii, inducing higher stresses and fatigue loading at the region where these two portions meet.
The upper deck floor structure is positioned adjacent or proximate this high stress and fatigue region, and is prone to movement, high stresses, and cyclic loading, during flight and on the ground. Existing proposed designs generally lack a mechanism or method for moderating, inhibiting, and/or limiting the load experienced by the upper deck floor structure as a result of supporting an integrated elevator and its support structure.
Furthermore, existing designs also generally lack a system for correcting the carriage ambient movement caused by fuselage shifting when the carriage is in a lower loading or unloading position near the ground.
In addition, generally conventional integrated elevator designs that use a carriage sized to transport individuals, cargo, and supplies, require excess space in the elevator shaft within the airplane. Therefore, these systems require excess modification to existing fuselage structures, making their installation impractical. To date, none of the existing designs have been practically incorporated in a multi-deck large aircraft such as the Boeing® 747® or multi-deck Airbus® aircraft.